CMC · California Mechanical Code

When do NFPA 85 requirements apply to boilers, stokers and steam generators?

Q: Does NFPA 85 apply to all steam generators, regardless of size?

No — § 1011.1 specifically lists steam generators used to recover heat from combustion turbines (those are subject to NFPA 85 regardless of size). Other boilers/steam equipment are subject to NFPA 85 when they meet the equipment type and the 12,500,000 Btu/h threshold.

If a boiler, stoker, pulverized‑fuel system, or atmospheric fluidized‑bed boiler has a fuel input rating of at least 12,500,000 Btu/h, or if a steam generator is used to recover combustion‑turbine exhaust heat, the California Mechanical Code requires design, installation and operation in accordance with NFPA 85 (see § 1011.1).

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Last reviewed: July 6, 2026

What the code requires — 2–4 sentences

The California Mechanical Code makes NFPA 85 the required standard for certain boilers, stokers and steam generators. The controlling rule is § 1011.1 (within § 1011.0) which says the design, installation and operation of specified boilers and steam generators must be in accordance with NFPA 85.
In short: if your equipment meets the types listed in § 1011.1 or is a steam generator used to recover heat from a combustion turbine (or its exhaust), NFPA 85 applies; portions of oil-burning systems that fall within NFPA 85’s scope must also be installed in accordance with NFPA 85.

The single most important rule: equipment types and certain applications listed in § 1011.1 are required to follow NFPA 85 — check the equipment type and the fuel input / application to determine applicability.

Requirements in detail

Core applicability language

The CMC’s Bo ilers, Stokers, and Steam Generators section is § 1011.0; the specific applicability sentence is in § 1011.1. That text identifies the equipment types and the fuel-input / application triggers for mandatory NFPA 85 compliance.

What equipment is named in § 1011.1

Single-burner boilers and multiple-burner boilers (when they meet the threshold described).
Stokers and atmospheric fluidized‑bed boilers (when they meet the threshold described).
Pulverized-fuel systems meeting the stated fuel-input threshold.
Fired or unfired steam generators used to recover heat from combustion turbines and to other combustion turbine exhaust systems — NFPA 85 applies to these regardless of the fuel‑input threshold language (they are listed explicitly).
Portions of oil‑burning systems that are covered by NFPA 85 must be installed in accordance with NFPA 85.

Decision matrix (quick reference)

Decision dimension	Value / threshold	NFPA 85 required?	Code Reference
Equipment is a single or multiple burner boiler, stoker, or atmospheric fluidized‑bed boiler AND fuel input ≥ 12,500,000 Btu/h (12.5×10^6 Btu/h; ~3.663 MW)	≥ 12,500,000 Btu/h	Yes — NFPA 85 applies	§ 1011.1
Equipment is a pulverized‑fuel system meeting the same fuel‑input threshold	≥ 12,500,000 Btu/h	Yes — NFPA 85 applies	§ 1011.1
Equipment is a fired or unfired steam generator used to recover heat from a combustion turbine (or for other combustion turbine exhaust systems)	Any size / input (explicitly listed)	Yes — NFPA 85 applies regardless of input in § 1011.1	§ 1011.1
Portion of an oil‑burning system that is inside NFPA 85 scope	—	That portion must be installed in accordance with NFPA 85	§ 1011.1
Boiler construction standard (general)	ASME BPVC Section I or IV OR NFPA 85	Manufacturer / installation must comply with one of these standards	§ 1002.0

(Note: the CMC text shows the numeric threshold and lists the named applications in § 1011.1. Use that section as the primary applicability test.)

What NFPA 85 covers (as adopted by the CMC)

Where NFPA 85 is required by § 1011.1, the design, installation, and operation of the named equipment must be in accordance with NFPA 85. The CMC also adopts NFPA 85 for specified control and safety device requirements for larger/covered equipment (see control‑device tables in Chapter 10 that reference NFPA 85).

Exceptions & special cases

The CMC text specifically makes the steam‑recovery application (combustion turbine heat recovery and exhaust systems) subject to NFPA 85 regardless of input; therefore do not rely solely on the fuel‑input threshold for HRSGs (heat‑recovery steam generators). § 1011.1 must be read literally for those cases.
The code text as provided uses the phrase relating the 12.5 E+06 Btu/h threshold and lists equipment types; the scanned excerpt has dense phrasing. If the application or manufacturer’s rating is ambiguous, the Authority Having Jurisdiction (AHJ) should be consulted — the CMC requires that AHJ inspections and approvals occur before service. § 1013.1 addresses inspections and the AHJ’s authority.
Boiler construction may instead comply via ASME BPVC Section I or IV where NFPA 85 is not invoked — see § 1002.0. If a boiler is already complying under ASME code and does not otherwise fall under § 1011.1, NFPA 85 is not automatically required.

If any nuance or exception that you need is not clearly stated in the excerpts available here, that specific nuance is not covered in the retrieved text and should be resolved by consulting the full CMC text, NFPA 85 itself, or the AHJ; I will state when source text does not cover an item. (See “Common mistakes” below for examples.)

Common mistakes

Misreading the numeric threshold — the code threshold is 12,500,000 Btu/h (written in the code as 12.5 E+06 Btu/h, ≈ 3.663 MW). Confusing 12.5E+06 with 1.25E+06 will lead to incorrect applicability. § 1011.1.
Assuming NFPA 85 applies only by fuel‑input and overlooking the explicit listing of steam generators used to recover heat from combustion turbines — those are called out in § 1011.1 and are subject to NFPA 85 regardless of the input threshold.
Applying NFPA 85 only to “packaged” or only to “large” boilers without checking the specific equipment type and application named in § 1011.1. The CMC’s Chapter 10 lists construction standard options (ASME or NFPA 85) — consult § 1002.0 when in doubt.
Failing to apply NFPA 85 to portions of oil‑burning systems that the section specifically says must be installed per NFPA 85. Don’t treat oil system components as exempt if they fall inside NFPA 85 scope. § 1011.1.

Worked example — concrete scenario

Scenario: A new plant installs a heat‑recovery steam generator (HRSG) to recover exhaust heat from a 30 MW combustion turbine. The HRSG rating (steam side) is listed with a burner equivalency input of 2,000,000 Btu/h.

Step 1 — Which sentence in the CMC controls? § 1011.1 explicitly lists “fired or unfired steam generators used to recover heat from combustion turbines and to other combustion turbine exhaust systems” as subject to NFPA 85. That language applies regardless of the numeric fuel‑input threshold.
Conclusion: NFPA 85 applies to the HRSG and its applicable systems and controls even though the numeric burner‑input (2,000,000 Btu/h) is less than 12,500,000 Btu/h. Design, installation and operation must comply with NFPA 85 as adopted by § 1011.1.

If instead you had a multiple‑burner steam boiler whose total burner input is 13,000,000 Btu/h, then it meets the numeric threshold and falls squarely within § 1011.1’s applicability, so NFPA 85 would apply.

Related provisions

§ 1011.0 — Boilers, Stokers, and Steam Generators (section heading that contains § 1011.1).
§ 1011.1 — General applicability language requiring NFPA 85 where named.
§ 1002.0 — Standards: boilers may be constructed/installed per ASME BPVC Section I, Section IV, or NFPA 85. Use when determining whether NFPA 85 or ASME controls construction.
§ 1003.2.1 / Table 1003.2.1 — Control and limit device requirements for boilers; several entries reference “Per NFPA 85” for equipment groups (see CMC Chapter 10 tables).
§ 1013.1 — Inspections and tests; the AHJ must inspect and approve installations before service (relevant when AHJ determination of applicability is needed).
§ 1014.1 — Operation and maintenance: AHJ authority to require operation and maintenance per nationally recognized standards.
§ 904.5 — Temperature or pressure limiting devices for boilers (example of other boiler controls referenced elsewhere in Chapter 9 / 10).

If you want, I can pull the exact full text of § 1011.1 and the relevant table rows from Chapter 10 so you can see the verbatim language and the related NFPA 85 cross‑references.

Code references

Grounded in the retrieved California Mechanical Code — click a citation to read the verbatim passage:

CMC § 92.9 High relevance — show source text
(3) 1000 square foot (92.9 m [2] ) heating surface

Power boilers that do not exceed one of the following limits:

(1) 5 000 000 Btu/h input (1464 kW)

(2) 5000 pounds steam per hour (0.6299 kg/s) capacity (3) 1000 square foot (92.9 m [2] ) heating surface

Boilers with manholes on top of the boiler, except those described in Section 1010.2 and Section 1010.4, shall have a clearance of not less than 3 feet (914 mm) from the top of the boiler to the ceiling. 1010.4 Package Boilers, Steam-Heating Boilers, and Hot-Water-Heating Boilers. Package boilers, steam-heating boilers, and hot-water-heating boilers with no manhole on top of the shell and not exceeding one of the above limits shall have a clearance of not less than 2 feet (610 mm) from the ceiling.

1011.0 Boilers, Stokers, and Steam Generators.

1011.1 General. The design, installation, and operation of single burner boilers, multiple burner boilers, stokers, and atmospheric fluidized-bed boilers with not less than a fuel input rating of 12.5 E+06 Btu/h (3.663 MW) to pulverized fuel systems, fired or unfired steam generators used to recover heat from combustion turbines and to other combustion turbine exhaust systems shall be in accordance with NFPA 85. That portion of the oil-burning system supplied on boilers and covered within the scope of NFPA 85 shall be installed in accordance with NFPA 85.

1012.0 Operating Adjustments and Instructions. 1012.1 General. Hot water boiler installations, upon completion, shall have controls set, adjusted, and tested by the installing contractor. A complete control diagram of a permanent legible type, together with complete boiler operating instructions, shall be furnished by the installer for each installation.

1013.0 Inspections and Tests. 1013.1 General. An installation for which a permit is required shall not be put into service until it has been inspected and approved by the Authority Having Jurisdiction.

It shall be the duty of the owner or his authorized representative to notify the Authority Having Jurisdiction that the installation is ready for inspection and test. It also shall be the duty of the owner or his authorized representative to post in a conspicuous position on the installation a notice in substantially the following form: “WARNING! THIS INSTALLATION HAS NOT BEEN INSPECTED AND APPROVED

BY THE AUTHORITY HAVING JURISDICTION AND

SHALL NOT BE COVERED OR CONCEALED UNTIL SO INSPECTED AND APPROVED,” and it shall be unlawful for anyone other than the Authority Having Jurisdiction to remove such notice. The Authority Having Jurisdiction shall require such tests as it deems necessary to determine that the installation is in accordance with the provision of this section. Such tests shall be made by the owner or his authorized representative in the presence of the Authority Having Jurisdiction.

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BOILERS AND PRESSURE VESSELS
CMC § 1010.0 High relevance — show source text
1010.0 Clearance for Access.

1010.1 General. Where boilers are installed or replaced, clearance shall be provided to allow access for inspection, maintenance, and repair. Passageways around all sides of boilers shall have an unobstructed width of not less than 18 inches (457 mm). Clearance for repair and cleaning shall be permitted to be provided through a door or access panel into another area, provided the opening is of sufficient size.

Exception: Subject to the approval of the Authority Having Jurisdiction, boilers shall be permitted to be installed with a side clearance of less than 18 inches (457 mm), provided that the lesser clearance does not inhibit inspection, maintenance, or repair.

1010.2 Power Boilers. Power boilers having a steam-generating capacity in excess of 5000 pounds per hour (lb/h) (0.6299 kg/s) or having a heating surface in excess of 1000 square feet (92.9 m [2] ) or input in excess of 5 000 000 Btu/h (1464 kW) shall have a clearance of not less than 7 feet (2134 mm) from the top of the boiler to the ceiling.

1010.3 Steam-Heating Boilers, Hot Water Boilers, and Power Boilers. Steam-heating boilers and hot-water-heating boilers that exceed one of the following limits:

(1) 5 000 000 Btu/h input (1464 kW)

(2) 5000 pounds steam per hour (0.6299 kg/s) capacity

(3) 1000 square foot (92.9 m [2] ) heating surface

Power boilers that do not exceed one of the following limits:

(1) 5 000 000 Btu/h input (1464 kW)

(2) 5000 pounds steam per hour (0.6299 kg/s) capacity (3) 1000 square foot (92.9 m [2] ) heating surface

Boilers with manholes on top of the boiler, except those described in Section 1010.2 and Section 1010.4, shall have a clearance of not less than 3 feet (914 mm) from the top of the boiler to the ceiling. 1010.4 Package Boilers, Steam-Heating Boilers, and Hot-Water-Heating Boilers. Package boilers, steam-heating boilers, and hot-water-heating boilers with no manhole on top of the shell and not exceeding one of the above limits shall have a clearance of not less than 2 feet (610 mm) from the ceiling.

1011.0 Boilers, Stokers, and Steam Generators.

1011.1 General. The design, installation, and operation of single burner boilers, multiple burner boilers, stokers, and atmospheric fluidized-bed boilers with not less than a fuel input rating of 12.5 E+06 Btu/h (3.663 MW) to pulverized fuel systems, fired or unfired steam generators used to recover heat from combustion turbines and to other combustion turbine exhaust systems shall be in accordance with NFPA 85. That portion of the oil-burning system supplied on boilers and covered within the scope of NFPA 85 shall be installed in accordance with NFPA 85.
CMC § 1005.0 High relevance — show source text
1005.0 Safety or Relief Valve Discharge . . 219

1005.1 General. . . . . . . . . . . . . . . . . . . . . 219

1005.2 Discharge Piping . . . . . . . . . . . . . 219

1005.3 Splash Shield . . . . . . . . . . . . . . . . 219

1005.4 Hazardous Discharge . . . . . . . . . . 219

1005.5 Vacuum Relief Valve . . . . . . . . . . 219

1006.0 Shutoff Valves . . . . . . . . . . . . . . . 219

1006.1 General. . . . . . . . . . . . . . . . . . . . . 219

1007.0 Gas-Pressure Regulators . . . . . . . 219

1007.1 General. . . . . . . . . . . . . . . . . . . . . 219

1008.0 Low-Water Cutoff . . . . . . . . . . . . . 220

1008.1 General. . . . . . . . . . . . . . . . . . . . . 220

1009.0 Combustion Regulators Safety Valves . . . . . . . . . . . . . . . . 220

1009.1 General. . . . . . . . . . . . . . . . . . . . . 220

1010.0 Clearance for Access . . . . . . . . . . 220

1010.1 General. . . . . . . . . . . . . . . . . . . . . 220

1010.2 Power Boilers . . . . . . . . . . . . . . . . 220

1010.3 Steam-Heating Boilers, Hot Water Boilers, and Power Boilers. . 220

1010.4 Package Boilers, Steam-Heating Boilers, and Hot-Water-Heating Boilers. . . . . . . . . . . . . . . . . . . . . . 220

1011.0 Boilers, Stokers, and Steam

Generators . . . . . . . . . . . . . . . . . . 220

xxxviii

1011.1 General. . . . . . . . . . . . . . . . . . . . . 220

1012.0 Operating Adjustments and Instructions . . . . . . . . . . . . . . . . . . 220

1012.1 General. . . . . . . . . . . . . . . . . . . . . 220

1013.0 Inspections and Tests. . . . . . . . . . 220

1013.1 General. . . . . . . . . . . . . . . . . . . . . 220

1013.2 Operating Permit . . . . . . . . . . . . . 221

1013.3 Maintenance Inspection . . . . . . . . 221

1013.4 Power and Miniature Boilers. . . . . 221

1013.5 Steam-Heating and WaterHeating Boilers . . . . . . . . . . . . . . . 221
CMC § 1010.2 Medium relevance — show source text
1010.2 Power Boilers . . . . . . . . . . . . . . . . 220

1010.3 Steam-Heating Boilers, Hot Water Boilers, and Power Boilers. . 220

1010.4 Package Boilers, Steam-Heating Boilers, and Hot-Water-Heating Boilers. . . . . . . . . . . . . . . . . . . . . . 220

1011.0 Boilers, Stokers, and Steam

Generators . . . . . . . . . . . . . . . . . . 220

xxxviii

1011.1 General. . . . . . . . . . . . . . . . . . . . . 220

1012.0 Operating Adjustments and Instructions . . . . . . . . . . . . . . . . . . 220

1012.1 General. . . . . . . . . . . . . . . . . . . . . 220

1013.0 Inspections and Tests. . . . . . . . . . 220

1013.1 General. . . . . . . . . . . . . . . . . . . . . 220

1013.2 Operating Permit . . . . . . . . . . . . . 221

1013.3 Maintenance Inspection . . . . . . . . 221

1013.4 Power and Miniature Boilers. . . . . 221

1013.5 Steam-Heating and WaterHeating Boilers . . . . . . . . . . . . . . . 221

1013.6 Automatic Steam-Heating Boilers. . . . . . . . . . . . . . . . . . . . . . 221

1013.7 Unfired Pressure Vessels . . . . . . . 221

1014.0 Operation and Maintenance of

Boilers and Pressure Vessels. . . . 221

1014.1 General. . . . . . . . . . . . . . . . . . . . . 221

Table 1003.2.1 Controls and Limit Devices for

Automatic Boilers . . . . . . . . . . . . . 222

CHAPTER 11 REFRIGERATION . . . . . . . . . . . . 225

1101.0 General. . . . . . . . . . . . . . . . . . . . . 227

1101.1 Applicability. . . . . . . . . . . . . . . . . . 227

1101.2 Equipment . . . . . . . . . . . . . . . . . . 227

Part I Refrigeration Systems . . . . . . . . 227

1102.0 Refrigeration Systems . . . . . . . . . 227

1102.1 General. . . . . . . . . . . . . . . . . . . . . 227

1102.2 Ammonia Refrigeration Systems . . 227

1102.3 Refrigerants . . . . . . . . . . . . . . . . . 227

1103.0 Classification . . . . . . . . . . . . . . . . 227

1103.1 Classification of Refrigerants . . . . 227
CMC § 431.86 Medium relevance — show source text
86| |Boilers, hot water|Gas fired8|>2 500 000 Btu/h1, 4|82%Ec
2|82%Ec
2|82%Ec
2| |Boilers, hot water|Oil fired5|<300 000 Btu/h6, 7
for applications out-
side U.S.9|84%AFUE|84%AFUE|Appendix N of 10
CFR Part 430| |Boilers, hot water|Oil fired5|≥300 000 Btu/h and
≤2 500 000 Btu/h4|82%Et
3|82%Et
3|10 CFR Part 431.86| |Boilers, hot water|Oil fired5|>2 500 000 Btu/h1,4|84%Ec
2|84%Ec
2|84%Ec
2| |Boilers, steam|Gas fired|<300 000 Btu/h6
for applications out-
side U.S.9|80%AFUE|80%AFUE|Appendix N of 10
CFR Part 430| |Boilers, steam|Gas fired— all,
except natural draft|≥300 000 Btu/h and
≤2 500 000 Btu/h4|79%Et
3|79%Et
3|10 CFR Part 431.86| |Boilers, steam|Gas fired— all,
except natural draft|>2 500 000 Btu/h1, 4|79%Et
3|79%Et
3|79%Et
3| |Boilers, steam|Gas fired— natural
draft|≥300 000 Btu/h and
≤2 500 000 Btu/h4|77%Et
3|79%Et
3|79%Et
3| |Boilers, steam|Gas fired— natural
draft|>2 500 000 Btu/h1, 4|77%Et
3|79%Et
3|79%Et
3| |Boilers, steam|Oil fired5|<300 000 Btu/h6
for applications out-
side U.S.9|82%AFUE|82%AFUE|Appendix N of 10
CFR Part 430| |Boilers, steam|Oil fired5|≥300 000 Btu/h and
≤2 500 000 Btu/h4|81%Et
3|81%Et
3|10 CFR Part 431.86| |Boilers, steam|Oil fired5|>2 500 000 Btu/h1, 4|81%Et
3|81%Et
3|81%Et
3|

For SI units: 1000 British thermal units per hour = 0.293 kW

Notes: 1 These requirements apply to boilers with rated input of 8 000 000 Btu/h (2343 kW) or less that are not packaged boilers and to all packaged boilers. Minimum efficiency requirements for boilers cover all capacities of packaged boilers. 2 Ec = combustion efficiency (100 percent less flue losses). See reference document for detailed information.

California Mechanical Code Medium relevance — show source text

BOILERS AND PRESSURE VESSELS

CONTROL AND LIMIT DEVICE SYSTEM DESIGN11	Col2	Col3	Required	Required	Required	Required	Required	Required	Required	Required	Required	Per NFPA 85	Per NFPA 85
APPROVED FUEL SHUT- OFF10	APPROVED FUEL SHUT- OFF10	APPROVED FUEL SHUT- OFF10	Not Required	Not Required	Required	Required	Not Required	Not Required	Not Required	Required	Not Required	Per NFPA 85	Per NFPA 85
STEAM PRESSURE AND LOW WATER LIMIT CON- TROLS9	STEAM PRESSURE AND LOW WATER LIMIT CON- TROLS9	STEAM PRESSURE AND LOW WATER LIMIT CON- TROLS9	Required	Required	Required	Required	Required	Required	Required	Required	Required	Per ASME Power Boiler Code, Section 1 and NFPA 85	Per ASME Boiler & Pressure Code & NFPA 85
HOT WATER TEMPERA- TURE AND LOW WATER LIMIT CON- TROLS8	HOT WATER TEMPERA- TURE AND LOW WATER LIMIT CON- TROLS8	HOT WATER TEMPERA- TURE AND LOW WATER LIMIT CON- TROLS8	Required	Required	Required	Required	Required	Required	Required	Required	Required	Per ASME Power Boiler Code, Section 1 and NFPA 85	Per ASME Boiler & Pressure Code & NFPA 85
PRE- PURGING CONTROL7	PRE- PURGING CONTROL7	PRE- PURGING CONTROL7	Not Required	Not Required	Required	Required	Not Required	Not Required	Not Required	Required	Not Required	Per NFPA 85	Per NFPA 85
LOW FIRE START UP CONTROL6	LOW FIRE START UP CONTROL6	LOW FIRE **START

CMC § 1001.3 Medium relevance — show source text
1001.3 Air for Combustion and Ventilation. Air for combustion and ventilation shall be provided in accordance with Chapter 7.

1001.4 Drainage. For heating or hot-water-supply boiler applications, the boiler room shall be equipped with a floor drain or other approved means for disposing of the accumulation of liquid wastes incident to cleaning, recharging, and routine maintenance. No steam pipe shall be directly connected to a part of a plumbing or drainage system, nor shall a water having a temperature above 140°F (60°C) be discharged under pressure directly into a part of a drainage system. Pipes from boilers shall discharge by means of indirect waste piping as determined by the Authority Having Jurisdiction or the boiler manufacturer’s instructions.

1001.5 Mounting. Equipment shall be set or mounted on a level base capable of supporting and distributing the weight contained thereon. Boilers, tanks, and equipment shall be securely anchored to the structure. Equipment requiring vibration isolation shall be installed as designed by a registered design professional and approved by the Authority Having Jurisdiction.

1001.5.1 Floors. Boilers shall be mounted on floors of noncombustible construction unless listed for mounting on combustible flooring. 1001.6 Chimneys or Vents. Boilers shall be connected to a chimney or vent, as provided for other fuel-burning equipment in Chapter 8 of this code.

1002.0 Standards.

1002.1 General. Pressure vessels shall be constructed and designed in accordance with the ASME Boiler & Pressure Vessel Code (BPVC) Section VIII.1. Boilers shall be constructed, designed, and installed in accordance with one of the following: (1) ASME BPVC Section I (2) ASME BPVC Section IV (3) NFPA 85 1002.2 Oil-Burning Boilers. Oil-burning boilers shall comply with Section 1002.2.1 and Section 1002.2.2. 1002.2.1 Listing & Labeling. Oil-burning boilers shall be listed and labeled in accordance with UL 726.

1002.2.2 Installation. Tanks, piping, and valves for oil-burning boilers shall be installed in accordance with NFPA 31.

1002.3 Electric Boilers. Electric boilers shall be listed and

labeled in accordance with UL 834.

1002.4 Solid-Fuel-Fired Boilers. Solid-fuel-fired boilers shall comply with UL 2523 and shall be installed in accordance with the manufacturer’s installation instruc tions.

1002.5 Dual Purpose Water Heaters. Water heaters utilized for combined space- and water-heating applications shall comply with the standards referenced in Table 1203.2, and shall be installed in accordance with the manufacturer’s

installation instructions.

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BOILERS AND PRESSURE VESSELS

1003.0 Detailed Requirements.

1003.1 Safety Requirements. The construction of boilers and pressure vessels and the installation thereof shall be in accordance with minimum requirements for safety from structural and mechanical failure and excessive pressures as established by the Authority Having Jurisdiction in accordance with nationally recognized standards.

CMC § 431.86 Medium relevance — show source text

For SI units: 1000 British thermal units per hour = 0.293 kW

Notes: 1 These requirements apply to boilers with rated input of 8 000 000 Btu/h (2343 kW) or less that are not packaged boilers and to all packaged boilers. Minimum efficiency requirements for boilers cover all capacities of packaged boilers. 2 Ec = combustion efficiency (100 percent less flue losses). See reference document for detailed information. 3 Et = thermal efficiency. See reference document for detailed information. 4 Maximum capacity—minimum and maximum ratings as provided for and allowed by the unit’s controls. 5 Includes oil-fired (residual). 6 Boilers shall not be equipped with a constant burning pilot light. 7 A boiler not equipped with a tankless domestic water-heating coil shall be equipped with an automatic means for adjusting the temperature of the water such that an incremental change in inferred heat load produces a corresponding incremental change in the temperature of the water supplied. 8 For new construction, refer to Section E 503.4 for additional system compliance requirements. 9 See Informative Appendix F, Table F-4 of ASHRAE 90.1, for U.S. minimum efficiencies for residential products covered by USDOE requirements for U.S. applications.

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APPENDIX E

TABLE E 503.7.1(7) PERFORMANCE REQUIREMENTS FOR HEAT REJECTION EQUIPMENT—MINIMUM EFFICIENCY REQUIREMENTS

[ASHRAE 90.1: TABLE 6.8.1-7]

EQUIPMENT TYPE	TOTAL SYSTEM HEAT- REJECTION CAPACITY AT RATED CONDITIONS	SUBCATEGORY OR RATING CONDITION8	PERFORMANCE REQUIRED1,2,3,6,7	TEST PROCEDURE4,5
Propeller or axial fan open- circuit cooling towers	All	95°F entering water 85°F leaving water 75°F entering wb	≥40.

CMC § 1003.2.1 Medium relevance — show source text

Required|Per
NFPA
85|Per
NFPA 85| |SAFETY CONTROL TIMING
(NOMINAL MAXIMUM TIME IN SECONDS)|TRIAL FOR MAIN
BURNER FRAME|DIRECT
ELECTRIC
IGNITION|Not
Required|15|15|15|90|30|15|15|Not
Required|Per
NFPA 85|Per
NFPA 85| |SAFETY CONTROL TIMING
(NOMINAL MAXIMUM TIME IN SECONDS)|TRIAL FOR
PILOT|TRIAL FOR
PILOT|90|15|15|15|Not
Required|Not
Required|Not
Required|15|Not
Required|10 sec
Per
NFPA 85|Per
NFPA 85| |TYPE OF
PILOT2|TYPE OF
PILOT2|TYPE OF
PILOT2|Any type|Interrupted
or
Intermittent|Interrupted
or
Intermittent|Interrupted|Any type|Interrupted|Interrupted|Interrupted|Not required|Any|None| |FUEL INPUT
RANGE1
(INCLUSIVE),
BTU/H|FUEL INPUT
RANGE1
(INCLUSIVE),
BTU/H|FUEL INPUT
RANGE1
(INCLUSIVE),
BTU/H|0 - 400 000|400 001 -
2 500 000|2 500 001 -
5 000 000|Over
5 000 000|0 - 400 000|400 001 -
1 000 000|1 000 001 -
3 000 000|Over
3 000 000|All|12 500 000
or more|Any| |FUEL|FUEL|FUEL|Gas|Gas|Gas|Gas|Oil|Oil|Oil|Oil|Electric|Gas, Oil
and/or
Coal|Heat
Recovery
Steam
Generator| |BOILER
GROUP|BOILER
GROUP|BOILER
GROUP|A|B|C|D|E|F|G|H|K|L|M|

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BOILERS AND PRESSURE VESSELS

FOOTNOTES FOR TABLE 1003.2.1 (continued)

1 Fuel input shall be determined by one of the following:

The burner input shall not exceed the input shown on the burner nameplate or as otherwise identified by the manufacturer.

The nominal boiler rating, as determined by the building official, plus 25 percent.

2 Automatic boilers shall have one flame failure device on each burner, which shall prove the presence of an ignition source at the point where it will ignite

CMC § 1014.0 Medium relevance — show source text

Where subject to corrosion and construction permits, they shall be subject to inspection internally biennially.

Inspection of boilers and pressure vessels covered by insurance shall be permitted to be made by employees of the insuring company holding commissions from the National Board of Boiler and Pressure Vessel Inspectors, subject to approval of the Authority Having Jurisdiction. Approved insuring company inspectors shall make reports on prescribed forms on inspections authorized by the Authority Having Jurisdiction. The reports shall be filed in the Authority Having Jurisdiction office. Company inspectors shall notify the Authority Having Jurisdiction of suspension of insurance because of dangerous conditions, new insurance in effect, and discontinuance of insurance

coverage.

1014.0 Operation and Maintenance of Boilers and Pressure Vessels.

1014.1 General. Boilers and pressure vessels shall be operated and maintained in accordance with requirements for pro

tection of the public established by the Authority Having Jurisdiction in accordance with nationally recognized standards.

The Authority Having Jurisdiction shall notify the owner or authorized representative of defects or deficiencies and properly corrected. Where such corrections are not made, or where the operation of the boiler or pressure vessel is deemed unsafe by the Authority Having Jurisdiction, they shall have the authority to revoke the permit to operate the boiler or pressure vessel. Where the operation of a boiler or pressure vessel is deemed by the Authority Having Jurisdiction to constitute an immediate danger, the pressure on such boiler or pressure vessel shall be permitted to be relieved at the owner’s cost and the boiler or pressure vessel shall not thereafter be operated without the approval of the Authority Having Jurisdiction.

2025 CALIFORNIA MECHANICAL CODE 221

BOILERS AND PRESSURE VESSELS

CONTROL AND LIMIT DEVICE SYSTEM DESIGN11	Col2	Col3	Required	Required	Required	Required	Required	Required	Required	Required	Required	Per NFPA 85	Per NFPA 85
APPROVED FUEL SHUT- OFF10	APPROVED FUEL SHUT- OFF10	APPROVED FUEL SHUT- OFF10	Not Required	Not Required	Required	Required	Not Required	Not Required	Not Required	Required	Not Required	Per NFPA 85	Per NFPA 85
STEAM PRESSURE AND LOW WATER LIMIT CON- TROLS9	STEAM PRESSURE AND LOW WATER LIMIT CON- TROLS9	STEAM PRESSURE AND LOW WATER LIMIT CON- TROLS9	Required	Required	Required	Required	Required	Required	Required	Required	Required	Per ASME Power Boiler Code,

CMC § 1102.3 Medium relevance — show source text
Chapter 10 Boilers and Pressure Vessels. Chapter 10 regulates the construction, installation, operation, repair, and alteration of boilers and pressure vessels. The safety provisions within this chapter address controls and limit devices for automatic boilers, methods of determining expansion tank capacities, discharge piping, relief valves, shutoff valves, gas-pressure and combustion regulators, and inspections and tests. Potable water heaters are free from the requirements of Chapter 10 as they are within the scope of the Uniform Plumbing Code (UPC).

Pressure vessels store large amounts of energy and must comply with ASME Boiler and Pressure Vessel Code (BPVC) Section VIII.1. The stored energy must be contained to prevent disastrous failures. Boilers must comply with ASME BPVC Section I, ASME BPVC Section IV, or NFPA 85. Installing a safety relief valve and expansion tank prevents pressures in the tank from exceeding the design threshold.

Chapter 11 Refrigeration. Chapter 11 regulates the design, installation, and construction requirements of refrigeration systems and the installation and construction of cooling towers. Refrigeration is a method used for achieving heat transfer to cool spaces. Refrigerants are the most common medium used to transfer the heat energy from the low-temperature level to the high-temperature level. Table

2025 CALIFORNIA MECHANICAL CODE xv

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

FORMAT OF THE UNIFORM MECHANICAL CODE

1102.3 lists the most commonly used refrigerants and is labeled by a number. The concentration limits provided in Table 1102.3 are useful for the quantity of refrigerant required to cool a volume of space safely.

A major milestone reached in the industry was the introduction of lower flammability refrigerants such as A2L and B2L. The industry’s concerns to address lower Global Warming Potential (GWP) refrigerants led to the development of these lower flammability refrigerants. Chapter 11 does not only include these lower flammability refrigerants in Table 1102.3, but it also contains specific A2L and B2L provisions to address the precautions necessary for the proper use of these products. In particular, high-probability systems using A2L refrigerants for human comfort applications are covered by provisions which include refrigerant concentration limits, mechanical ventilation, ignition sources, compressors and pressure vessels, and refrigerant sensors.

In addition, Chapter 11 addresses other minimum requirements for refrigeration systems such as refrigeration machinery rooms (including ventilation), relief valves, and pressure vessels. Apart from refrigerants, the chapter also addresses minimum requirements for systems that use other mediums such as ammonia and brine systems. For ammonia systems, such systems are required to comply with IIAR 2, IIAR 3, IIAR/ANSI 4, IIAR 5, and IIAR 6.

Chapter 12 Hydronics. Chapter 12 regulates hydronic systems that are part of heating, cooling, ventilation, and conditioning systems. Such piping systems include steam, hot water, radiant heating and cooling, chilled water, steam condensate, condenser water, ground source heat pump systems, snow and ice melt systems, ambient temperature loops, and district ambient temperature loops. Provisions within this chapter addressing ground source heat pumps and ambient temperature loops apply to the hydronic portions of the system. Geothermal energy systems, including ground source heat pumps and ambient temperature loops, are regulated by Chapter 17.
CMC § 2-4 Medium relevance — show source text

Section 1
and
NFPA 85|Per
ASME
Boiler &
Pressure
Code &
NFPA 85| |PRE-
PURGING
CONTROL7|PRE-
PURGING
CONTROL7|PRE-
PURGING
CONTROL7|Not
Required|Not
Required|Required|Required|Not
Required|Not
Required|Not
Required|Required|Not
Required|Per
NFPA 85|Per
NFPA 85| |LOW FIRE
START UP
CONTROL6|LOW FIRE
START UP
CONTROL6|LOW FIRE
START UP
CONTROL6|Not
Required|Not
Required|Required|Required|Not
Required|Not
Required|Not
Required|Required|Not
Required|Per
NFPA 85|Per
NFPA 85| |ASSURED
AIR SUP-
PLY CON-
TROL5|ASSURED
AIR SUP-
PLY CON-
TROL5|ASSURED
AIR SUP-
PLY CON-
TROL5|Required|Required|Required|Required|Required|Required|Required|Required|Not
Required|Per
NFPA 85|Per
NFPA 85| |ASSURED
FUEL SUP-
PLY CON-
TROL4|ASSURED
FUEL SUP-
PLY CON-
TROL4|ASSURED
FUEL SUP-
PLY CON-
TROL4|Not
Required|Not
Required|Required|Required|Not
Required|Required|Required|Required|Not
Required|Per
NFPA 85|Per
NFPA 85| |SAFETY CONTROL TIMING
(NOMINAL MAXIMUM TIME IN SECONDS)|MAIN
BURNER
FLAME
FAILURE3|MAIN
BURNER
FLAME
FAILURE3|90|2-4|2-4|2-4|90|2-4|2-4|2-4|Not
Required|Per
NFPA 85|Per
NFPA 85| |SAFETY CONTROL TIMING
(NOMINAL MAXIMUM TIME IN SECONDS)|TRIAL FOR MAIN
BURNER FRAME|FLAME
PILOT|90|15|15|15|90|30|15|60|Not
Required|Per
NFPA
85|Per
NFPA 85| |SAFETY CONTROL TIMING
(NOMINAL MAXIMUM TIME IN SECONDS)|TRIAL FOR MAIN
**BURNER

Frequently asked questions

Who decides whether NFPA 85 applies when the code text is ambiguous?

The Authority Having Jurisdiction (AHJ) makes final determinations and enforces inspections/approval per § 1013.1; consult the AHJ when manufacturer ratings or application details are unclear.

Does NFPA 85 apply to all steam generators, regardless of size?

No — § 1011.1 specifically lists steam generators used to recover heat from combustion turbines (those are subject to NFPA 85 regardless of size). Other boilers/steam equipment are subject to NFPA 85 when they meet the equipment type and the 12,500,000 Btu/h threshold.

If a boiler complies with ASME BPVC Section I, is NFPA 85 still required?

Boiler construction may comply with ASME BPVC Section I or IV or NFPA 85 per § 1002.0. However, if the installation meets § 1011.1’s applicability triggers (equipment type or HRSG/turbine‑recovery application), NFPA 85 is required for design/installation/operation regardless of construction code choice.

Are oil‑burning components treated differently?

The CMC states that “that portion of the oil‑burning system supplied on boilers and covered within the scope of NFPA 85 shall be installed in accordance with NFPA 85.” So any oil‑system components that fall within NFPA 85’s scope must comply. § 1011.1.

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